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News Corp’s Andrew Bolt, a strong promoter of the kind of material produced by Roberts, told the senator there were now “five or six out and proud voices of climate scepticism in the Senate”.

So how did Roberts respond to his newfound fame? Well, he didn’t disappoint, telling every mainstream audience there was “no empirical evidence to show that carbon dioxide affects the climate in any way”.

What about his conspiracy theories (he says they’re not conspiracies, just facts) that climate change is a scam pushed by global banks looking for cash and the UN on the hunt for global domination? Roberts didn’t disappoint there either.

On ABC Melbourne, host Rafael Epstein asked Roberts: “Do you think the UN’s trying to impose some sort of global government through climate change policy?”

For years, Roberts has been writing to politicians, government agencies, universities and scientists making the same claim that there is “no empirical evidence” to show fossil fuel burning causes climate change.

Empirical evidence?

So what does Roberts mean by “empirical evidence”? According to him, decisions should be based on “observations in the real world … it’s measured, real world data” and nothing else counts.

There are two very obvious problems with Roberts’ argument.

The “real world data” is sending a clear message that the Earth is gaining heat at a rapid rate and that this is a long-term trend. Whether you look at global air temperatures measured in the real world by thermometers or derived from satellites, or the temperature of the oceans at multiple depths, or the increasing frequency of extreme temperatures, or the rising sea levels, the melting ice sheets, the disappearing Arctic sea ice, the increasing risk of bushfires … we could go on and on with a parade of “empirical evidence”.

Anyone can claim there is no evidence if they refuse to look at it.

Professor Steven Sherwood, UNSW

At the same time, humans are adding CO2 to the atmosphere and oceans at a rate that groups like the Geological Society say are unprecedented “even in comparison with the massive injections of carbon to the atmosphere at the Palaeocene-Eocene boundary, which led to a major thermal event 55m years ago”.

Roberts’ argument that science is only about “empirical evidence” might sound all sciencey to his interviewees and the lay audience. But it’s bunk.

If all you rely on is “empirical evidence”, and reject modelling and analysis that uses that data, then you basically throw out large swathes of modern scientific endeavours.

Prof Steven Sherwood, director of the Climate Change Research Centre at the University of New South Wales, told me:

The argument is specious.

Anyone can claim there is no evidence if they refuse to look at it. In Galileo’s time, some people refused to look into his telescope and then claimed there was no evidence to support what he was saying. Same thing today.

The problem is that evidence does not stand up by itself and announce the answer to any given question. Evidence must be interpreted by humans. Scientists have all interpreted the evidence, going back decades, and unanimously agree that it proves beyond a reasonable doubt that (a) humans are increasing CO2 and (b) this is causing warming. There is not a single respectable atmospheric scientist in the world whom I know of, who disagrees with either of these conclusions (there are a handful who challenge the magnitude of the effect but that’s a different question).

It is impossible to make a prediction based on data alone. Only a model can make a prediction of anything that has not happened yet.

Denial suite

Roberts has built a whole suite of well-rehearsed arguments to enable him to reject any assertions put to him.

They go like this, and I’m paraphrasing here. Climate scientists only say it’s warming because if they didn’t their grants would dry up. The Bureau of Meteorology and CSIRO have corrupted climate science and are thus guilty of corruption. Government agencies are politicised, which means anything they produce cannot be trusted. You can’t trust climate models, so anything that comes from them should be chucked out.

[Roberts] has no understanding of how science works.

Professor Peter Doherty, Nobel winner

One of Australia’s most famous and celebrated scientists is Prof Peter Doherty, who, in 1996, was jointly awarded a Nobel prize for his research into the immune system.

Doherty told me he had sent Roberts “plenty of reports and material” but Roberts had ignored it.

So Doherty has first-hand experience with Roberts and also knows a bit about the scientific method. He told me:

I’ve never used the term ‘empirical evidence’, or heard any other working scientist say it. [Roberts] has no understanding of how science works.

Discoveries in science stem from a mix of hypothesis, experiment, data generation, data analysis, insight and even a bit of guesswork. Telling the story of what’s happening in something as complex as climate science further depends on integrating information from a diverse spectrum of fields, then designing to see if the conclusions are valid or false. There’s a constant process of correction and further interpretation that then has to be supported by measurement.

You can tell a genuine sceptic from a denier (as I discuss in The Knowledge Wars) because the sceptic will want to look at new data and conclusions and, like any real scientist, will modify their conclusions accordingly. The denier remains ‘locked in’ to a sort of ‘decerebrate rigidity’.

All good scientists are sceptical, not least about their own data and conclusions. Further data show that we’re wrong, and we prefer not to be wrong, so people change their positions with new evidence. And, if you want to understand very complex, interactive systems, you have to use modelling approaches.

With climate science, data is coming in from a very broad spectrum of scientific disciplines that no one person can pull together ... thus the IPCC.

So how should journalists react when a newly-minted senator makes claims that run against science academies across the planet while suggesting institutions and governments the world over – from the US military to the UN – are either part of, or have been hoodwinked by, a conspiracy that only he can and a few other people on the internet are able to see?

Deference? Respect? Polite engagement?

According to Doherty “you have to respect the institutions of our democracy, including the Australian Senate, but that does not mean you have to respect the viewpoints held by individual senators”.

So there is another approach journalists could take.

In 2013, Roberts sent one of his voluminous reports to Ben Cubby, then the environment editor at the Sydney Morning Herald. I’ll leave you with Cubby’s response.

In considering your request that I identify errors in the report you sent to me – CSIROh! Climate of Deception? Or First Step to Freedom? – I find myself confronting an unusual problem: how does one critically analyse a pile of horseshit?